Here is a possible route via the Delmarva Peninsula.
Of course, you could head due west from Lewes to the Bay Bridge,
but then you would miss all the special things that this area has to offer.
Once you cross the Delaware Bay, you leave the North and enter the South.
There is an immediate different feel as soon as you get out of touristy Lewes.
The little back roads will have almost zero traffic - even the highway be light.
(Your nose will tell you occasionally that mega chicken farms serve the big cities.)
In the South, there used to be country stores every 5 or 10 miles at intersections.
One gas pump, essential groceries, and plenty of Coca-Colas - with a bench out front.
They are mostly gone - there is one just west of Millsboro called "That Place" - classic.
Millsboro, Snow Hill, and Pocomoke City are the major service points in between.
The route will take a day and a half - with camping or lodging at Lewes and Pocomoke CIty.
Pocomoke River State Park has magnificent coastal swamp forests - a feel for early America.
It will be tricky to arrange a crossing of the Chesapeake Bay via Smith Island but worth it.
Especially with your wife driving - the Smith Island ferries are passenger/bike only.
Also, the ferry to Point Lookout doesn't start up until late May - you would need to charter
BUT - if you can rent a car from Highlands, New Jersey to Pocomoke -
(Enterprise will usually work out a drop-off - even 10 or 12 miles.)
Then you could both boar out to Smith Island and over to Point Lookout.
Your wife could arrange another Enterprise car from Lexington Park.
But, who wants to drive - esp. park - in New York City or Washington, DC?
The bike route up from Point Lookout is sweet - crossing over to Alexandria, VA -
with a lovely bike trail into DC at the Lincoln Memorial.
It's been quite a few years since I lived in New York or biked the Chesapeake -
There was actually better ferry service 25 years ago - same in Britain, probably.
But if you are interested, Smith Island will make your East Coast leg magical.
Best - J
https://ridewithgps.com/routes/26572433